1. Field of the Invention
The present invention relates to fuel cell reforming catalysts, methods of preparing the same, reformers for fuel cells, and fuel cell systems including the same.
2. Description of the Related Art
Fuel cells are power generation systems that produce electrical energy through an electrochemical redox reaction of oxygen and hydrogen in hydrocarbon-based materials such as methanol, ethanol, or natural gas. Fuel cells are clean energy sources that can replace fossil fuels.
A fuel cell includes a stack composed of unit cells and produces various ranges of power. Since fuel cells have four to ten times higher energy densities than small lithium batteries, they have been highlighted for use as small portable power sources.
Representative fuel cells include polymer electrolyte membrane fuel cells (PEMFCs) and direct oxidation fuel cells (DOFCs). Direct oxidation fuel cells include direct methanol fuel cells (DMFCs) which use methanol as the fuel.
In the above-mentioned fuel cell system, the stack that generates electricity includes several to scores of unit cells stacked adjacent to one another. Each unit cell is formed of a membrane-electrode assembly (MEA) and a separator (also referred to as a bipolar plate). The membrane-electrode assembly is composed of an anode and a cathode which are separated by a polymer electrolyte membrane. A fuel is supplied to the anode and adsorbed on anode catalysts. The fuel is then oxidized to produce protons and electrons. The electrons are transferred to the cathode via an external circuit, and the protons are transferred to the cathode through the polymer electrolyte membrane. In addition, an oxidant is supplied to the cathode. Then, the oxidant, protons, and electrons are reacted on cathode catalysts to produce electricity and water.
Polymer electrolyte fuel cells have high energy densities and high power but require the careful handling of hydrogen gas and require accessory facilities for producing hydrogen as the fuel gas such as fuel reforming processors for reforming methane or methanol, natural gas, or the like.
In general, hydrogen is produced from hydrocarbons such as methane through a reforming reaction such as a steam reforming reaction, a partial oxidation reaction, a carbon dioxide reforming reaction, or a combination of a partial oxidation reaction and a steam reforming reaction.